def func(score):
    if score>100:
        return 'wrong score'
    elif score>=90:
        return 'A'
    elif score>=80:
        return 'B'
    elif score>=70:
        return 'C'
    elif score>=60:
        return 'D'
    elif score>=0:
        return 'E'
    else:
        return 'wrong score'


print(func(100))
print(func(80))
print(func(50))
print(func(-1))


